<style type="text/css">
	body { margin:0; }
	.p1{ top:20px; height:50px; width:150px; background-color:blue;}
	.p2{ top:10px; left:20px; height:30px; width:100px; background-color:yellow;}
	.p3{ top:0px; left:50px; height:100px; width:50px; background-color:red;}
</style>
<body>
<div style="position:relative;" class="p1">1
    <div style="position:absolute; z-index:1;" class="p2">2</div>
</div>
<div style="position:absolute;" class="p3">3</div>
</body>